RAPID: Assessing flow rate of Macondo oil spill

在这场灾难中，石油的流速问题已成为一个核心问题，主要有两个原因：（1）指导应对工作需要知道石油在哪里，在哪里的表面，以及它被冲到哪个海岸上;（2）确定哪些技术可以用来密封油井，关键取决于知道流速。5月20日，海军上将艾伦成立了流速技术小组（FRTG），以解决石油流速的问题。Wewey教授被任命为该团队的成员。经过一个月的计算和对各种流动情景的审议，FRTG确定最有可能的石油流量仅为35，000至60，000桶/天，不包括甲烷或其他气态烃。FRTG主要使用远程操作车辆（ROV）拍摄的视频，因为很少有其他仪器可用。通过各种方法分析视频以估计油的流速。FRTG的一些成员使用粒子图像测速（PIV）代码来跟踪油射流外表面的相干结构，以确定其速度。从喷射的表面速度，必须估计喷射的平均速度。这一步存在相当大的不确定性。虽然射流文献的主体跨越至少100年，但这里的特定场景是独特的：不同性质的加热的、不混溶的、不透明的流喷射到无界储层中的两相流。文献对外部结构速度和射流平均速度之间的关系提供了一些指导，但这种关系仍然是流速估计值的上限和下限之间的范围几乎为2的原因。这里提出的是一套实验室实验，尽可能接近地复制石油流入海水的实际情况。视频将采取的流动和分析的方式类似于FRTG的程序。由于实验是在实验室中进行的，因此可以知道油射流的平均流速，并且可以很好地了解外表面特征速度与平均射流速度之间的关系。首先，为溢油对峙分析的新方法提供了坚实的理论基础。第二，将探讨特定类别喷流的物理学。 这项活动的广泛影响是相当大的。目前的流速估计值为35，000至60，000桶/天，其范围几乎为2，这是过大的，在很大程度上是由于外部可跟踪的相干结构速度与射流平均速度之间的不确定关系。这里的工作目标是大大缩小这个范围。更准确地了解溢油流量对于指导正在发生的灾难和未来肯定会发生的灾难中的溢油响应至关重要。

The issue of the flow rate of oil during this disaster has become a central issue for primarily two reasons: (1) directing the response requires knowing where the oil where surface and which shores it wash up on and (2) determining which technologies can be used to seal the well depends critically on knowing the flow rate. On May 20, Admiral Allen created the Flow Rate Technical Group (FRTG) to address the question of oil flow rate. Prof. Wereley was appointed a member of this team. After a month of calculations and deliberations over various flow scenarios, the FRTG determined that the most likely flow rate of oil was 35,000 to 60,000 bbl/day of oil only, not including methane or other gaseous hydrocarbons. The FRTG primarily used videos shot by remote operated vehicles (ROVs) because very little other instrumentation was available. The videos were analyzed by various methods to estimate the flow rate of the oil. A number of members of the FRTG used particle image velocimetry (PIV) codes to track the coherent structures at the outer surface of the oil jet to determine its speed. From the surface speed of the jet, the average speed of the jet had to be estimated. There is considerable uncertainty in this step. While the body of jet flow literature spans at least 100 years, the particular scenario here is unique: two phase flow of a heated, immiscible, opaque flow of different properties ejecting into an unbounded reservoir. The literature provided some guidance on what the relationship was between the outer structure speed and the average speed of the jet but this relationship remains the reason that the range between the upper and lower bounds of the flow rate estimate represents nearly a factor of 2. What is proposed here is a set of laboratory experiments that would as closely as possible replicate the actual situation of oil flowing into sea water. Video would be taken of the flows and analyzed in a manner similar to the FRTG's procedure. Because the experiments are conducted in a lab, the average flow rate of the oil jet will be known and a very good idea of the relationship between the outer surface feature speed and the average jet speed can be found.The intellectual merit of this activity is two-fold. First, a new method for stand-off analysis of oil spills will be given a solid theoretical base. Second, the physics of a specific class of jets will be explored. The broader impacts of this activity are considerable. The nearly factor of 2 range on the current flow rate estimate of 35,000 to 60,000 bbl/day are excessively large and due, in large part, to the uncertain relationship between the outer trackable, coherent structure speed and the average speed of the jet. The goal of the work here is to considerably narrow this range. Having a more precise knowledge of the oil spill flow rate is critical to directing the oil spill response both in the on-going disaster and in future disaster which are certain to happen.